Journal
CHEMISTRY-A EUROPEAN JOURNAL
Volume 14, Issue 5, Pages 1482-1491Publisher
WILEY-V C H VERLAG GMBH
DOI: 10.1002/chem.200701522
Keywords
cyclization; gold; homogeneous catalysis; platinum; synthetic methods
Categories
Ask authors/readers for more resources
Chemo- and stereoselective transformations of 3-hydroxy-1,5-allenynes 1 into a variety of new and potentially useful cyclic compounds have been achieved. Substrates bearing a silyl group at the alkyne moiety undergo purely thermal or Lewis acid catalyzed Alder-ene type transformations into 2-methylene-3-vinylcyclopent-3-enol derivatives 2. When heated in the presence of a catalytic amount of PtCl2 or PtCl4, these incipient cyclopentenols could be further transformed into 3-vinylcyclopent-2-enones 3. On the other hand, alkyl-substituted 3-hydroxy-1,5-allenynes proved to be stable under refluxing conditions. Nevertheless, PtCl2 and PtCl4 could selectively activate the alkyne moiety of these substrates toward intramolecular nucleophilic attack of the internal allene double bond to yield unprecedented 6-methylenebicyclo[3.1.0]hexan-3-one derivatives 4. With gold-based catalysts, provided that the reaction is carried out in dichloromethane, both An(I) and An(III) complexes selectively activate the allene fragment of the substrates toward intramolecular nucleophilic attack of the hydroxyl group to yield 2-ethynyl-3,6-dihydro-2H-pyrans 5. Compounds of type 4 can also be formed with An(I) and Au-III complexes if the reaction is carried out in toluene. The reactivity of these new compounds has been partially investigated, and polycyclic ketones were obtained after oxidation under mild conditions or gold-catalyzed cycloisomerization.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available